NTSB Factual Report

On July 23, 2004, about 0520 Pacific daylight time, an Air Tractor AT-502B, N5010E, collided with high vegetation and terrain during initial climb from a dirt airstrip about 2 miles south of Mendota, California. Thiel Air Care, Inc., operated the airplane under the provisions of 14 CFR Part 137. The commercial pilot was not injured; the airplane was substantially damaged. Visual meteorological conditions prevailed, and a flight plan had not been filed. The aerial application flight was originating at the time of the accident.

In the pilot's completed "Aircraft Accident Report" he indicated that, at 1930 the previous day, he began performing aerial application flights. The accident occurred upon initiation of the pilot's 21st consecutive flight, which was to be the last of his work shift.

The pilot reported familiarity with the airstrip, which he described as being in "excellent" condition. Logistically, because of the placement of his water supply at the south end of the airstrip, the pilot opted to takeoff in a northerly direction. The wind was nearly calm. The pilot reported that he was aware of the presence of a 5- to 6-foot-tall corn crop near the north end of the 2,600-foot-long airstrip. The airplane's left and right side spray tanks were 3/4 and 1/2 full, respectively.

In pertinent part, the pilot reported the following sequence of events transpired immediately preceding his takeoff and during the accident flight:

Prior to takeoff, I was directing the crew about preparations for the next day and was discussing events that had occurred during the previous night. Upon initiation of the takeoff, I failed to apply the 10 degrees of wing flaps that I had utilized on my previous takeoffs. At approximately 60 knots, when the tail should have been starting to respond and did not, I began introducing wing flaps, but there was no response. I continued exercising the flap switch with no response. The tail came up farther down the runway than normal but with some buffet. With approximately 200 feet of runway left, I attempted to dump my load and make the airplane fly as quickly as possible, and I failed to hit my dump handle. The airplane came off the ground approximately 20 feet from the end of the runway, but I could not gain sufficient altitude to clear the corn. The airplane continued to fly through the corn but would not climb. I initiated a shallow turn toward a shorter crop, but the airplane stalled and the left main wheel struck the ground. Thereafter, the left wing impacted the ground, and the airplane cartwheeled at least three times before coming to rest inverted in the field.

NTSB Probable Cause

The pilot's inadequate preflight/pretakeoff procedure by not lowering the wing flaps, which resulted in an inadvertent stall as the pilot attempted to climb out of ground effect to clear a corn crop at the end of the runway. A factor in the accident was the failure, for undetermined reasons, of the flaps to deploy during the takeoff roll when the pilot moved the switch.